@Meddler AP Kog'Maw buffs?
AP Kog'Maw was nerfed a few patches back because he started seeing play for his incredible wave clear and long range burst. His main ability, his E void Ooze, had the base damage nerfed and AP scaling nerfed. In patch 6.24 it went from 60 / 110 / 160 / 210 / 260 to 60 / 105 / 150 / 195 / 240, and the AP ratio was reduced from 70% AP to 50% AP. In the same patch Rylai's, a core item for AP Kog'Maw, was nerfed heavily.
Looking at op.gg in NA, and minding the small sample size, AP Kog went from a 54% win rate and 0.22% play rate in patch 7.1, to a 41% win rate and 0.17% play rate in 7.5. Given the sample size I'm not going to take these numbers as gospel, but the difference in win rate is fairly ridiculous. Generally anything under 48% win rate is considered under powered. 41% win rate might as well be completely dumpstered.
The only things AP Kog'Maw now brings to the table over other mages now are his long range burst, resistance reduction, and his % max health AA modifier. He really just doesn't stand up to the current mid lane or mage metas.
Just because AP Kog'Maw is an off-build does not mean it should be dumpstered and forgotten the instant it was seen as viable. Meddler, give AP Kog'Maw some form of compensation for his multiple nerfs. To nerf a champion like this and just leave it is borderline cruelty to the people that play them.